There's a saying in the US: 'What's good for Detroit is good for America.'

But William Clay Ford Jr turns that kind of logic on its head. For him, what's good for America, and indeed the planet, is good for Detroit.

Ford is an unlikely person to have his feet under the top table of the second-biggest car manufacturer in the world - even if his great-grandfather was Henry, the man who started it all with the Model T.

Despite the sharp grey suits, gleaming manicure and soft boyish looks that shout thrusting corporate high-flyer, Ford Motor Company's iconoclastic 43-year-old chairman has more in common with Greenpeace activists than Wall Street analysts. His great-grandfather was a major cog in the industrial revolution, he says; what's needed this century is a 'clean' revolution.

'I believe very strongly that corporations could and should be a major force for resolving social and environmental concerns in the twentyfirst century,' he told a Greenpeace conference last month. 'As chairman of one of the world's largest corporations I am in a unique position to be a catalyst for change.'

Not your usual mission statement from a car company boss, but Bill Ford is not your usual car company boss. 'There are people who think I'm a Bolshevik, and this is all a major distraction at best and heresy at worst,' he has said. 'But I really don't care. I'm in this for my children [he has four] and my grandchildren. I want them to inherit a legacy they're proud of. I don't want anybody, whether it's my grandchildren or any of our employees' grandchildren, to have to apologise for working for Ford Motor Company. In fact, I want the opposite. I want them to look and say, "What a difference we made!".'

Fortune magazine said Ford was blazing new ground at the steering wheel of an old-economy company: 'Here comes an entirely new old-economy boss. A nice guy with a politician's keen instinct.'

And a nice guy he plainly is. When news reached the company of a catastrophic explosion at the Rouge factory in Dearborn, Michigan in February 1999, Ford immediately went to the scene, despite strenuous advice not to do so by lieutenants, who warned he could be eaten alive by the media.

Without an entourage he visited the injured and dying in hospital until late into the night (six people died), and was on television describing it as the 'worst day of my life'.

Three months later Ford ordered an environmental makeover of the plant, which his great-grandfather built, vowing to turn it into the world's first closed-loop car production facility - producing cars whose component parts are so many 'technical nutrients' that will be recy cled one day in new cars.

A self-described 'life-long environmentalist' who began fraternising with environmental groups during his student days at Princeton and MIT, Ford has painted the executive suite an electrifying shade of green since he became chairman two years ago.

Ford Motor Company has since become the first and only car maker to certify all 140 plants around the world under ISO 14001, the international management standard that audits environmental performance.

Bill Ford also courted controversy on Wall Street by pulling his company out of the Global Climate Coalition and lobbying for higher petrol taxes. Last summer he initiated discussions between environmental groups and senior Ford managers. At the Greenpeace conference he went further and took up the environmental groups' challenge to follow BP's John Browne in accepting climate change as reality - heresy in corporate America.

'Anyone who disagrees is, in my view, still in denial. We at Ford Motor Company have moved on,' he says.

The remarks are bound to have caused ructions in Detroit. But being a renegade is nothing new for Ford. When he joined the family firm 20 years ago he was asked to stop associating with green groups and told it would damage his career. 'I wonder what they'd think of me now,' he says with a smirk. 'I'd ask them, but they are no longer with the company.'

But the climb up the corporate ladder was not an easy one - even for a Ford. He has worked his way up through 17 positions in the 20 years since joining the company straight from university. At first he called himself Bill Clay. Before he became chairman in 1998 he had to battle hardline opposition from some on the board - including the former CEO - to his environmental agenda. His relationship with new chief executive Jacques Nasser, is said by some insiders to be rocky.

But Ford has doggedly pursued his ideals, maintaining that what is good for the planet is good for Ford. He points to ISO 14001. 'It's saving us millions of dollars a year in energy, water, materials and waste-handling costs.'

The company is also repositioning itself as a purveyor of mobility. 'The day will come when the notion of car ownership becomes antiquated. If you live in a city, you don't need to own a car.' He sees a future where Ford owns vehicles and makes them available to motorists as and when they need access to transport.

In the shorter term Ford is spending $1billion to put a family car on the road by 2004 that runs on hydrogen, emitting only water from its exhaust. Ford says the P2000 will be the Model T of the twentyfirst century, setting the standard for others to follow. Ford also promises to have a hybrid-electric sports utility vehicle, powered by a conventional engine as well as electric motor, on the market by 2003.

The problem for Bill Ford is that sports utes are hugely profitable - the company earns about $8,000 profit for each Explorer sold in the US. Which may go some way to explaining how an even petrol-thirstier behemoth like the Excursion, which does 10 miles to the gallon, must be accommodated in Bill Ford's clean, green future.

Ford tries to reconcile this by making the 'greenest' sports utes in the industry. More than 80 per cent of the Explorer is recyclable and all Ford sports utes sold in the US and Canada are certified as low-emission vehicles.

'As long as gas is cheaper than bottled water, we can't be in a position of dictating to the consumer what to buy,' says Bill Ford.

Geoff Lye, director of SustainAbility, the UK environmental consultancy that has been working with Ford, says: 'I don't think any other major automotive manufacturer has that passion and commitment to the environment at the top.'